I went with the Simrad TP22 over the Raymarine for the following reasons:

1) cheaper - i could get a more powerful pilot for the same money. With the unbalanced rudder causing a heavy helm, I expect I will need it (I also plan to mount it further forward)

2) non-proprietary signals - by my understanding, the Raymarine serious only works with data from other Raymarine hardware (steer to wind, steer to course). The simrad works with the Simnet signals, AND standard NMEA signals (so I can hook it up to my garmin GPS and non-simrad wind gauge)